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FERMI is a single-pass FEL user-facility designed to cover the wavelength range from 100 nm to 4 nm in the first harmonic. It uses a linear accelerator to generate a beam of relativistic electrons that is made to propagate through a long series of undulators. A conventional laser superposed to the electron beam in the first undulator (seeding) is utilized to induce coherent emission, which is exponentially amplified when the electrons propagate through the following undulator magnetic field. Among existing FEL sources FERMI is unique in many respects. The implemented seeded FEL scheme guarantees the generation of high transversely and longitudinally coherent pulses and the use of APPLE II-type undulators allows for variable polarization, from completely linear both horizontally and vertically to circular in both directions.

FERMI light source

Free Electron Laser

Facility Overview

FERMI entered in operation for users since January 1st, 2019, at the conclusion of its construction and commissioning phase, also with the contribution of external users. Here the list of intermediate achieved goals.Description